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Scant CO2 Benefit from China’s Coal-Powered Electric Cars

From Green-Weiskel et al, “Electric Vehicles in the Context of Sustainable Development in China.”China’s plan to build millions of electric vehicles will have little impact on the country’s carbon dioxide emissions, a new analysis concludes, because so much of the country’s electricity is produced by burning coal. The graph shows what the carbon dioxide emissions would be from an electric vehicle, a Nissan Leaf, in various Chinese provinces (bars at left) compared to emissions from a similar, but gas-powered Nissan model, the Tiida.

Doug Kanter for The New York TimesChinese leaders plan to make the country one of the leading producers of hybrid and all-electric vehicles. (Video report.)

She explains that in all but three grid regions in China, electric vehicles produce more CO2 per mile because of the coal source for the power than the equivalent gasoline-powered car:

Electric vehicles are often propped up as the key technological innovation to solve the global climate crisis. But in coal-dependent China, electric vehicles can actually have a larger carbon footprint than their traditional internal combustion engine counterparts.

Electric cars are only as environmentally friendly as the electricity grid from which they pull their energy. In China, those grids aren’t very clean. China produces about 37 percent of the world’s coal, and consumes roughly three times more coal than the US on an annual basis. According to the State Bureau of Statistics, 80 percent of electricity in China is generated from coal with contributions from hydro at 17 percent, nuclear 2 percent and “wind and other” at a measly 0.7 percent.

In a recent UN-commissioned study I conducted with Dr. Feng An, Liping Kang and Robert Earley, my colleagues at the Innovation Center for Energy and Transportation, a policy center based in Beijing, we found that in only three of the seven electricity grid regions in China does an EV have a lower carbon footprint than a traditional internal combustion engine vehicle. We compared a life-cycle analysis of the all-electric Nissan Leaf with the Nissan Tiida – a traditional car with a gasoline-fueled internal combustion engine that is comparable in body and chassis and overall user experience. In the graph below the vertical axis shows grams of carbon dioxide equivalent per kilometer driven. The horizontal axis shows the different electricity grids across China: North China Grid, North East Grid, Central China Grid, South China Grid, Hainan Power Grid and the average for the Nissan Leaf. We found that GHG emission changes range from a 23 percent reduction to a 36 percent increase over the Tiida. On average (represented by the red bar), the footprint of the Nissan Leaf was bigger than the footprint of the Tiida for both the automatic (AT) and manual transmission (MT) models.

A brief side note, especially for Prius owners: If this same study were conducted in the United States the results would be far more encouraging. The U.S. consumes a lot of coal, but still far less than China. Over 50 percent of electricity in the U.S. comes from lower carbon sources of energy like hydro, nuclear, natural gas, wind and solar and just 45 percent comes from dirty coal. This means that an EV driven in the U.S. would have a much smaller carbon footprint than if that same vehicle were driven in China.

It is important to make the point here that electric vehicles are still a key (if not central) part of a low-carbon future in any country. The above study should not be misunderstood as anti-EV. Instead the study makes one simple point: EV development must be coupled with reform of the electric grid away from coal and towards cleaner sources of energy. The hard truth is that as long as China is addicted to coal, one million new electric vehicles a year won’t amount to any positive climate impact.

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By 2050 or so, the human population is expected to pass nine billion. Those billions will be seeking food, water and other resources on a planet where humans are already shaping climate and the web of life. Dot Earth was created by Andrew Revkin in October 2007 -- in part with support from a John Simon Guggenheim Fellowship -- to explore ways to balance human needs and the planet's limits.